The present invention relates to rolling bearings, in particular rolling bearings having an inner ring and an outer ring with one or more rows of rolling elements held by a cage between bearing races provided on the two rings. The rolling elements can, for example, be balls. The rolling bearings may be, for example, those used in industrial electric motors or in motor vehicle gearboxes. In such applications, the bearings are mainly loaded radially, often with a relatively weak load compared to the capacity of the bearings used. The rotational speeds in such applications are of the order of 3000 rpm. In such applications, the service life of the rolling bearing is essentially related to the lubrication of the bearing. Any defect in lubricating the bearing generally leads to rapid degradation and to failure of the bearing.
Deep-groove rolling bearings with a single row balls conventionally have seals or sealing flanges which can be lubricated “for life” by the grease initially located inside the bearing, circumferentially between the balls and radially between the bearing races. However, in the long term, the mixing of the grease, combined with its ageing and with the heating cycles that the bearing undergoes, cause the grease to degrade. It is possible to envisage periodic regreasing operations for this type of rolling bearings. However, these operations are expensive.
Patent application WO 2006/041040 (NTN) and German patent application DE 1 016 404 disclose a rolling bearing which has an independent lubricant reservoir that can be housed between the two rings of the bearing. The lubricant can be supplied onto the balls of the bearing by a radial duct delimited partly by a face of one of the rings of the rolling bearing and by a wall of the lubricant reservoir. Such a construction is complicated and expensive.
German patent application DE 10 2005 033 566 (Schaeffler), moreover, discloses a rolling bearing without clearance, in which the outer ring is in two parts. One of the parts of this ring is obtained by stamping sheet metal and delimits, together with a housing holding the two parts of the ring, a space, inside which an axially preloaded resilient element is housed. However, this document provides no particular means of lubricating the rolling bearing.
British patent application GB 1 245 451 (SKF) also discloses a rolling bearing with two rings and an annular housing surrounding one of the rings, and also a closed space filled with lubricant. European patent application EP 0 769 631 (Snecma) for its part shows a ball bearing having lubricant passages made in one of the rings. None of these known constructions allows satisfactory lubrication of the rolling elements in a genuinely effective and economic manner.